Electronic component-built-in module

ABSTRACT

A module includes an electronic component having at least two electrodes, a board having electrodes on its surface to be connected to the electrodes of the electronic component, respectively, solders for connecting the electrodes of the electronic component to the electrodes of the board, respectively, an insulating resin covering the electronic component, the surface of the board, the solder, and the electrodes, and solder resists provided on the surface of the board and around the electrodes of the board, respectively. One of the solder resists is separated from the other electrode at a portion between the electronic component and the board. When this module is mounted on a motherboard, the solder does not flow out of the electrodes even when the solder in the insulating resin melts.

This application is a U.S. National Phase Application of PCTInternational Application PCT/JP2003/016427.

TECHNICAL FIELD

The present invention relates to a module accommodating an electroniccomponent, and more particularly to a module including a wiring board,electronic components arranged on an upper surface of the board, and aninsulating resin for covering the electronic components.

BACKGROUND ART

Recently, small electronic devices are widely used which devices includea module with built-in electronic components which includes a board,plural electronic components arranged on the board, and a resin mold forcovering the electronic components. FIG. 17 is a sectional view ofconventional module 101 with a electronic component molded with resin.Wiring board 102 has a surface having wiring pattern 111 and electrode103 thereon, and the surface is covered with solder resist 106. Wiringboard 102 has inner via 110 electrically connecting wiring pattern 112and backside electrode 113 formed on the backside of wiring board 102.Backside electrode 113 is provided with solder 114 for connecting theelectrode to a motherboard (not illustrated). Electronic component 104and electrode 103 are connected with solder 105, and then the surface ofwiring board 102 is covered with insulating resin 107 so as to wrapelectronic component 104. The surface of module 101 is provided withmetal-plated, electromagnetic shield layer 115 thereon.

In conventional module 101, electronic component 104 is mounted and onwiring board 102, and wired with solder and bonding wires.

The mounting with bonding wires requires a larger area than that ofelectronic component 104 for joining with wires, thus making the moduleunsuitable for reducing the size of electronic devices.

Meanwhile, The mounting with solder requires an area substantiallyidentical to the size of the electronic component although fillet at anend of electrode 103 is needed, thus making the module suitable forreducing the size of electronic devices. However, in order to preventshort-circuit due to the solder, portions except for the electrodes onthe surface of wiring board 102 are required to cover with solder resist106. In order to prevent short-circuit between electrodes upon itsmounting, a very small amount of solder is used. Therefore, clearance107A between electronic component 104 and wiring board 102 covered withsolder resist 106 after the mounting is approximately maximum 10 μm.When electronic component 104 is molded with insulating resin 107, theresin 107 does not flow into clearance 107A sufficiently, hence causinga space in the clearance.

If module 101 having the space in clearance 107A is joined to themotherboard with solder, solder 105 may melt in module 101, and themelting solder 105 flows into clearance 107A. Consequently, the soldercauses short-circuiting failure between electrodes 103, hence ruining afunction of module 101.

In order to fill clearance 107A between electronic component 104 andwiring board 102 with the insulating resin, the vacuum printing methodis proposed. The insulating resin often contains inorganic filler, suchas SiO₂, having a particle diameter of several dozen micrometers.Therefore, it is difficult to fill clearance 107A of approximately 10 μmwith an insulating resin even by the vacuum printing method.

Clearance 107A between electronic component 104 and photo-resist 106 maybe filled with underfill having a particle diameter less than 10 μm.However, such underfill is very expensive since being made offinely-classified inorganic filler.

FIG. 18 is a sectional view of another conventional module with built-inelectronic components molded with an insulating resin. Wiring board 1102has a surface having wiring pattern 1111 thereon and electrode 1103. Thesurface is covered with solder resist 1116. Wiring board 1102 isprovided with inner via 1110 and wiring pattern 1112 therein. Wiringboard 1102 is provided with backside electrode 1113 and solder 1114 onthe backside electrode. Electrode 1106 of electronic component 1104 andelectrode 1103 of wiring board 1102 are connected with solder 1105, andthen the surface of wiring board 1102 is covered with insulating resin1107 so as to wrap electronic component 1104. Module 1110 hasmetal-plated, electromagnetic shield layer 1115 thereon.

Module 1100 is mounted on a motherboard with reflow soldering. In thiscase, solder 1105 in module 1100 melts and has its volume expanding. Thevolume expansion of solder 1105 may apply a stress to electroniccomponent 1104, so that the stress will tear electronic component 1104from portion 1107A of insulating resin 1107 intervening betweenelectronic component 1104 and wiring board 1102. Consequently, solder1105 may flow out between electronic component 1104 and insulating resin1107, hence causing short-circuiting between electrodes 1103.

Conventional modules similar to above-mentioned ones are disclosed inJapanese Patent Laid-Open Publication Nos.2001-24312, 11-163583, and2001-168493.

SUMMERY OF THE INVENTION

A module includes an electronic component having at least twoelectrodes, a board having electrodes on its surface to be connected tothe electrodes of the electronic component, respectively, solders forconnecting the electrodes of the electronic component to the electrodesof the board, respectively, an insulating resin covering the electroniccomponent, the surface of the board, the solder, and the electrodes, andsolder resists provided on the surface of the board and around theelectrodes of the board, respectively. One of the solder resists isseparated from the other electrode at a portion between the electroniccomponent and the board.

When this module is mounted on a motherboard, the solder does not flowout of the electrodes even when the solder in the insulating resinmelts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a sectional view of a module according to ExemplaryEmbodiment 1 of the present invention.

FIG. 1B illustrates the module and a motherboard having the modulemounted thereon according to Embodiment 1.

FIG. 2 is a top view of a wiring board of the module according toEmbodiment 1.

FIG. 3 is a top view of the wiring board of the module according toEmbodiment 1.

FIG. 4 is a sectional view of a module according to Exemplary Embodiment2 of the invention.

FIG. 5 is a sectional view of a module according to Exemplary Embodiment3 of the invention.

FIG. 6 is a top view of a wiring board of the module according toEmbodiment 3.

FIG. 7 is a sectional view of the module according to Embodiment 3.

FIG. 8 is a top view of the wiring board of the module according toEmbodiment 3.

FIG. 9 is a sectional view of a module according to Exemplary Embodiment4 of the invention.

FIG. 10 is a top view of a wiring board of the module according toEmbodiment 4.

FIG. 11 is a sectional view of the module according to Embodiment 4.

FIG. 12 is a top view of a wiring board of the module according toEmbodiment 4.

FIG. 13A is a sectional view of a module according to ExemplaryEmbodiment 5 of the invention.

FIG. 13B illustrates the module and a motherboard having the modulemounted thereon according to Embodiment 5.

FIG. 14A is a front view of an electronic component in modules accordingto Embodiments 5 to 7.

FIG. 14B is a sectional view of a wiring board of the modules accordingto Embodiments 5 through 7.

FIG. 15 is a sectional view of the module according to Embodiment 6.

FIG. 16 is a sectional view of the module according to Embodiment 7.

FIG. 17 is a sectional view of a conventional module.

FIG. 18 is a sectional view of another conventional module.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Exemplary Embodiment 1

FIG. 1A is a sectional view of module 1 with built-in electroniccomponent 4 accommodated therein according to Exemplary Embodiment 1 ofthe present invention. Multi-layered wiring board 2 includes electrode 3and wiring pattern 11 on surface 2A, and includes wiring pattern 12 andinner via 10 inside of wiring board 2. Backside 2B has backsideelectrode 13 solder resist 6 thereon.

FIG. 2 is a top view of two electrodes 3 to be connected to electroniccomponent 4 and the periphery of electrodes 3 on wiring board 2.Electrode 3 on surface 2A of wiring board 2 is surrounded by solderresist 6. Solder resist 6 is formed only around electrode 3. Solderresists 6 around electrodes 3 adjacent to each other are separated fromeach other and are not connected to each other at the bottom ofelectronic component 4, hence making a sufficient clearance betweenelectronic component 4 and wiring board 2. Consequently, the clearancebetween electronic component 4 and wiring board 2 is easily filled withportion 7A, a first insulating resin, of insulating resin 7. Further,insulating resin 7 and part 7A contact wiring board 2. This arrangementreduces the area of insulating resin 7 contacting solder resist 6 havinglow adhesion with the insulating resin, hence allowing insulating resin7 to be bonded on wiring board 2 firmly.

FIG. 3 is a top view of electrodes 3 on wiring board 2 which areconnected to plural electronic components 4 and the peripheries ofelectrodes 3. The portions other than bottoms of electronic components 4are easily filled with resin 7, and thus, solder resists 6 aroundrespective electrodes 3 to be connected to electronic components 4adjacent to each other may be connected.

Wiring patterns 11 and 12 are made of Cu foil, however may be made ofanother conductive substance, such as conductive resin composition.

Inner via 10 may be made of conductive substance having a thermosettingproperty. The conductive substance may be conductive resin compositionincluding mixture of metallic particles and thermosetting resin. Themetallic particles may be Au, Ag, or Cu, Au, Ag, and Cu are preferablefor their high conductivity, and Cu is particularly preferable since CUhas a high conductivity, low migration profile and is inexpensive. Thethermosetting resin may be epoxy resin, phenol resin, or cyanate resin.The epoxy resin particularly preferable for its high heat resistance.

Electronic component 4 is mounted with solder 5 on a predeterminedposition of wiring board 2. Electronic component 4 may be a chip-likecomponent, such as a resistance, capacitor, and inductor, or asurface-mounting, passive component, such as an oscillator and filter.

FIG. 1B shows module 1 and motherboard 90 having module 1 mountedthereon. Solder 14 of module 1 is connected to electrode 91 onmotherboard 90. Solder 5 may be Pb—Sn eutectic solder, and may bePb-free solder of Sn—Ag—Cu, Au—Sn, or Sn—Zn. Solder 5 for mountingelectronic component 4 may be made of material different from oridentical to that of solder 14 for mounting module 1 on motherboard 90.The solders may be Pb-free solders, which are preferable for recentenvironmental issues.

Insulating resin 7 covering electronic component 4 completely is made ofmixture of inorganic filler and thermosetting resin. The inorganicfiller may be substance, such as Al₂O₃, MgO, BN, AlN, SiO₂, and BaTiO₃.The inorganic filler is preferably contained in resin 7 by a rateranging from 50 wt. % to 95 wt. %. This range allows insulating resin 7to have a wall thickness (for example, 1 mm) beyond the height ofelectronic component 4. If the rate of the inorganic filler is less than50 wt %, insulating resin 7 has a large fluidity, and can not have thewall thickness more than the height of electronic component 4.Meanwhile, if insulating resin 7 containing more than 95 wt. % of theinorganic filler has a fluidity to small to completely cover electroniccomponent 4. The particle diameter of the inorganic filler is smallerthan the clearance of a portion excluding solder resist 6 between wiringboard 2 and electronic component 4. The particle diameter enables theclearance between electronic component 4 and wiring board 2 to be easilyfilled with the insulating resin. The thermosetting, insulating resincontained in insulating resin 7 may be epoxy resin, phenol resin, orcyanate resin as the thermosetting resin, and preferably may be theepoxy resin since the epoxy resin has a high heat resistance.

Insulating resin 7 has a surface having metal film 15 provided thereonfunctioning as an electromagnetic shield. Metal film 15 may be made ofat least one of metallic materials, such as Au, Ag, Cu, Ni, Cr, Zn, Ti,Al, and Sn.

As shown in FIG. 1A, the thickness of solder resist 6 and a lifting ofelectronic component 4 occurring when electronic component 4 is mountedwith solder 5 creates a space having a height of approximately 50 μmbetween electronic component 4 and wiring board 2. The particle diameterof the inorganic filler contained in insulating resin 7 is determined tobe less than 50 μm, which is a clearance between electronic component 4and wiring board 2, and enables the clearance to be easily filled withinsulating resin 7. Further, inorganic filler having a particle diameterless than 10 μm is not required, and insulating resin 7 can be formed tohave a thickness (for example, 1 mm) beyond the height of electroniccomponent 4. The inorganic filler having the large particle diameter of50 μm is inexpensive.

Since insulating resin 7 contacts wiring board 2, the area of insulatingresin 7 that contacts solder resist 6, which has a low adhesion, issmall, hence allowing insulating resin 7 to be firmly bonded to wiringboard 2.

The above-mentioned structure allows the clearance between electroniccomponent 4 and wiring board 2 to be easily filled with insulating resin7. The structure allows insulating resin 7 to functions as a wall forpreventing solder 5 from flowing out even if solder 5 melts when module1 is mounted on motherboard 90, hence preventing a short-circuitingbetween electrodes 3.

The insulating resin 7 has a bending modulus preferably less than 20GPa. In the case that the modulus is more than 20 GPa, when a stresscaused by the volume expansion caused by the melting of solder 5 isapplied to insulating resin 7, a stress to suppress the volume expansionof solder 5 also occurs. These stresses do not balance with each other,hence resulting in a crack in insulating resin 7. Then, melting solder 5flows into the crack, hence causing the characteristic of module 1 todeteriorate. Insulating resin 7 having a bending modulus less than 20GPa can deform according to the volume expansion caused by the meltingof solder 5. Accordingly, insulating resin 7 does not have the crackgenerated therein, hence preventing melting solder 5 to flow into it.Therefore, module 1 does not have short-circuit trouble due to thesolder and has characteristics not deteriorate.

Exemplary Embodiment 2

FIG. 4 is a sectional view of module 1B with built-in electroniccomponent 4 according to Exemplary Embodiment 2 of the presentinvention. The same elements as those of Embodiment 1 are denoted by thesame reference numerals and are not described in detail. Insulatingresin 7B is formed around electronic component 4 and is made of materialsimilar to that of insulating resin 7 shown in FIG. 1A according toEmbodiment 1. As shown in FIG. 4, similarly to Embodiment 1, solderresist 6 is formed only around electrode 3, hence providing a largeclearance between electronic component 4 and wiring board. The clearancebetween electronic component 4 and wiring board 2 is filled withinsulating resin 8, and then, electronic component 4, insulating resin8, and insulating resin 7B for covering wiring board 2 are provided.Then, metal film 15 functioning as an electromagnetic shield is formedon the surface of insulating resin 7B.

Insulating resin 8 is made of mixture containing inorganic filler andthermosetting resin. The inorganic filler may be substance, such asAl₂O₃, MgO, BN, AlN, SiO₂, and BaTiO₃. The inorganic filler is containedby a rate ranging from 10 wt. % to 70 wt. % in insulating resin 8.Insulating resin 8 is required to have a high fluidity enough to fillthe clearance between electronic component 4 and wiring board 2.Insulating resin 8 does not necessarily have a thick portion on theouter surface of electronic component 4, which is differently frominsulating resin 7B, and hence, includes the inorganic filler by therate smaller than that of insulating resin 7B. In other words, a firstinsulating resin of module 1 according to Embodiment 1 shown in FIG. 1corresponds to insulating resin 8 and insulating resin 7B, which aresecond and third insulating resins, respectively, in module 1B shown inFIG. 4 according to Embodiment 2. Insulating resin 7B is positioned at aside of electronic component 4 opposite to board 2.

Insulating resin 8 functions as a wall between electronic component 4and wiring board 2 for preventing solder from flowing out when solder 5melts. If insulating resin 8 does not contain inorganic filler at all,the resin has a very high fluidity, hence allowing solder 5 to easilyflow out, that is, hence preventing insulating resin 8 from functioningas the wall. Therefore, insulating resin 8 needs to contain inorganicfiller. In consideration of the wall function and the fluidity,inorganic filler is contained insulating resin 8 preferably by a rateranging from 10 wt. % to 70 wt. %. This rate allows the clearancebetween electronic component 4 and wiring board 2 to be easily filledwith insulating resin 8.

Similarly to Embodiment 1, since contacting wiring board 2, insulatingresin 8 is bonded to wiring board 2 firmly.

Similarly to insulating resin 7B, insulating resin 8 preferably has abending modulus less than 20 GPa. If insulating resin 8 is made ofmaterial with a bending modulus more than 20 GPa, two types of stressesare applied to insulating resin 8: a stress caused by a volume expansiondue to melting of solder 5, and a stress preventing the volume expansionof solder 5. These stresses do not balance each other, and insulatingresin 8 has a crack generated therein, hence allowing melting solder 5to flow into the crack and having characteristics of module 1A todeteriorate. Insulating resin 8 having a bending modulus less than 20GPa deforms according to the volume expansion due to the melting ofsolder 5. Consequently, insulating resin 8 does not have a crack formedtherein, hence preventing melting solder 5 from flowing out. Thisprevents short-circuiting due to the solder, and prevents thecharacteristics of module 1A from deteriorating.

Exemplary Embodiment 3

FIG. 5 is a sectional view of module 1C with the built-in electroniccomponent according to Exemplary Embodiment 3 of the present invention.FIG. 6 is a top view of wiring board 2C of module 1C according toEmbodiment 3. FIG. 7 is a sectional view of another module 1D accordingto Embodiment 3, and FIG. 8 is a top view of wiring board 2D of module1D according to Embodiment 3. The same elements as those of Embodiment 1are denoted by the same reference numerals and are not described detail.

As shown in FIGS. 5 and 6, similarly to Embodiment 1, in module 1C,solder resists 6 and 6C are formed only around electrodes 3 on thesurface of wiring board 2C. Electronic component 4 is mounted withsolder 5, and electronic component 24 is mounted with solder 25.

Electronic component 24 is a surface-mounted, active component includinga semiconductor device, such as a transistor, IC, and LSI. Similarly toEmbodiment 1, insulating resin 7 having a height more than heights ofelectronic components 4 and 24 is provided. A clearance betweenelectronic component 24 and wiring board 2 is determined to be more thana clearance between wiring board 2 and electronic component 4, a passivecomponent. Electrode 23 of electronic component 24 is positioned on asurface of component 24 facing board 2C, and does not have a fillet ofsolder 5 formed thereon, unlike electronic component 4. Consequently,solder 25 spreads the clearance between electronic component 24 andwiring board 2 like a column. This structure allows the surface ofwiring board 2 over which electronic component 24 is positioned to becovered with solder resist 6C except a position where electrode 23 ismounted. Another module 1D shown in FIGS. 7 and 8 includes solder resist6D only around electrode 3 to have electronic component 24 mountedthereon.

Modules 1C and 1D can incorporate both active component 24 and passivecomponent 4, hence accomplishing a number of functions.

Exemplary Embodiment 4

FIG. 9 is a sectional view of module 1E with a built-in electroniccomponent according to exemplary Embodiment 4 of the present invention,and FIG. 10 is a top view of wiring board 2E of module 1E. FIG. 11 is asectional view of another module 1F according to Embodiment 4, and FIG.12 is a top view of wiring board 2F of module 1F. The same elements asthose of Embodiments 1 to 3 are denoted by the same reference numeralsand are not described in detail.

An area of electronic component 24, an active component, is larger thanthat of electronic component 4, so that the difference in thermalexpansion coefficients between electronic component 24 and wiring board2 tends to cause a connection defect. As shown in FIG. 9, in order toreduce the difference of thermal expansion coefficients, the clearancebetween electronic component 24 and wiring board 2 is filled withinsulating resin 9 having a thermal expansion coefficient larger thanthose of electronic component 24 and wiring board 2.

Electronic component 4 has a solder fillet. If the clearance betweenelectronic component 4 and wiring board 2 is filled with insulatingresin 9 having a large thermal expansion coefficient, a temperature ofmodule 1E reaches a temperature higher than the melting point of solderwhen module 1E is mounted on a motherboard by reflow soldering.Consequently, according to expansion of insulating resin 9, solder 5 istorn apart from electrode 3 on wiring board 2. Then, solder 5 is cooledbelow the melting point, and has its volume contract. However, thevolume expansion of insulating resin 9 is still large, hence allowingsolder 5 to be solidified and to be separated from electrode 3. Namely,the reflow soldering causes a break between solder 5 and electrode 3,and the break prevents the clearance between electronic component 4 andwiring board 2 from being filled with insulating resin 9.

As shown in FIGS. 9 and 10, electronic component 4 is covered withinsulating resin 7 having a thermal expansion coefficient smaller thanthat of insulating resin 9. In order to control a portion coated withinsulating resin 9, solder resist 26 to be a wall for preventinginsulating resin 9 from flowing out is formed between electroniccomponent 24 and electronic component 4.

According to Embodiment 4, similarly to embodiment 3, the surface ofwiring board 2 where electronic component 24 is mounted may be coveredwith solder resist 6E, excluding a portion for electrode 3. In module 1Fshown in FIGS. 11 and 12, the surface of wiring board 24 whereelectronic component 24 is mounted has solder resist 6F thereon onlyaround electrode 3.

Modules 1E and 1F can incorporate both active component 24 and passivecomponent 4, hence accomplishing a number of functions.

Exemplary Embodiment 5

FIG. 13A is a sectional view of module 1001 with built-in electroniccomponent 1004 according to Exemplary Embodiment 5 of the presentinvention. FIG. 14A illustrates electronic component 1004. FIG. 14Billustrates electrode 1003 on wiring board 1002 incorporated in module1001.

Multi-layered wiring board 1002 includes electrode 1003 and wiringpattern 1012 on surface 1002A, inner via 1010 in the inner layer, andbackside electrode 1013 on backside 1002B. Solder 1014 is provided onbackside electrode 1013, and solder resist 1016 for surrounding solder1014 is provided on backside 1002B of wiring board 1002. Electrodes 1003and 1013, and wiring pattern 1012 are made of Cu foil, andalternatively, may be made of another conductive substance, such asconductive resin composition. Inner via 1010 is made of conductivesubstance having a thermosetting property, such as conductive resincomposition of mixture of metallic particles and thermosetting resin.The metallic particles may preferably be Au, Ag, or Cu for their highconductivities, and particularly, may more preferably be Cu since Cu hasa high conductivity and low migration, and is inexpensive. Thethermosetting resin may preferably be epoxy resin, phenol resin, orcyanate resin, and particularly, may more preferably br epoxy resin forits high heat resistance.

Electronic component 1004 having electrodes 1006 on both ends thereof ismounted on wiring board 1002 with solder 1005. Electronic component 1004may be an active component, such as a semiconductor device including atransistor, IC, LSI, or surface-mounted, passive components, such as aresistance, capacitor, inductor, oscillator, and filter.

FIG. 13B shows module 1001 and motherboard 1090 having module 1001mounted thereon. Solder 1014 of module 1001 is connected to electrode1091 on motherboard 1090. Solder 1005 may be Pb—Sn eutectic solder orPb-free solder of Sn—Ag—Cu, Au—Sn, or Sn—Zn. These materials has meltingpoints less than 230° C., thus allowing electronic component 1004 not tobe heat-resistant. Solder 1005 for mounting electronic component 1004may be made of material different from or identical to that of solder1014 for mounting module 1001 on motherboard 1090. Solders 1005 and 1004may preferably be Pb-free solder for recent environmental issues.

Insulating resin 1007 covers electronic component 1004 completely andenter into a clearance between electronic component 1004 and wiringboard 1002. Insulating resin 1007 is made of mixture of inorganic fillerand thermosetting resin. The inorganic filler may be substance, such asAl₂O₃, MgO, BN, AlN, SiO₂, and BaTiO₃. The inorganic filler is containedin insulating resin 1007 by a rate a ranging from 50 wt. % to 95 wt. %.This rate allows insulating resin 1007 to form a thickness (for example,1 mm) beyond the height of electronic component 1004. If the rate isless than 50 wt. %, insulating resin 1007 has a large fluidity, hencebeing prevented from forming the above-mentioned wall thickness. It isdifficult to prepare insulating resin 1007 containing more than 95 wt. %of inorganic filler. The inorganic filler has a particle diameter lessthan the clearance (L1) between wiring board 1002 and electroniccomponent 1004. The particle diameter allows the clearance betweenelectronic component 1004 and wiring board 1002 to be easily filled withinsulating resin 1007. The thermosetting resin contained in insulatingresin 1007 may preferably be epoxy resin, phenol resin, or cyanateresin, and may more preferably be epoxy resin for its high heatresistance.

Insulating resin 1007 has a surface having metal film 1015 formedthereon for functioning as an electromagnetic shield. Metal film 1015may be made of at least one of metallic material, such as Au, Ag, Cu,Ni, Cr, Zn, Ti, Al, and Sn.

As shown in FIGS. 14A and 14B, in module 1001, distance (S_(C)) betweenelectrodes 1006 of electronic component 1004 and distance (S_(S))between electrodes 1003 of wiring board 1002 satisfy the relationS_(C)≧S_(S). According to the relation, when solder 1005 melts whilemodule 1001 is mounted on the motherboard, a stress caused by a volumeexpansion due to melting of solder 1005 urging portion part 1007A ofinsulating resin 1007 between electronic component 1004 and wiring board1002 toward electronic component 1004. This urging prevents solder 1005from flow into the clearance between electronic component 1004 andinsulating resin 1007, hence preventing short-circuiting between theelectrodes due to the melting of solder 1005.

Solder 1005 is formed to have angle α between the bottom surface ofelectronic component 1004 and contour 1005A at the bottom of electroniccomponent 1004 be an obtuse angle more than 90°. Solder 1005 has angle βbetween the contour of solder 1005 and electrode 1003 be an acute angleless than 90°. Namely, contours 1005A of solder 1005 extends indirections approaching each other as advancing from electronic component1004 to wiring board 1002. This structure allows a portion of solder1005 at the bottom of electronic component 1004 expands so that theportion of solder 1005 urges portion 1007A of insulating resin 1007between electronic component 1004 and wiring board 1002 towardelectronic component 1004. Accordingly, the interface between electroniccomponent 1004 and insulating resin 1007A contacts firmly, hencepreventing solder 1005 from flowing out. However, when insulating resin1007 is hardened, wiring board 1002 and insulating resin 1007 can befirmly bonded to each other since both insulating resin 1007 and wiringboard 1002 are made of resin. Therefore, wiring board 1002 andinsulating resin 1007 can be bonded firmly against a stress caused bythe expansion of solder 1005, hence preventing solder 1005 from flowinginto the interface between wiring board 1002 and insulating resin 1007.

It is important that angle α between the bottom surface of electroniccomponent 1004 facing solder 1005 and the contour of solder 1005 doesnot become an acute angle.

Insulating resin 1007 is made of material having a bending modulus lessthan 20 GPa to reduce an influence of the expansion of solder 1005.

Exemplary Embodiment 6

FIG. 15 is a sectional view of module 1001A with built-in electroniccomponent 1006 according to Exemplary Embodiment 6 of the presentinvention. The same elements as those of Embodiment 5 are denoted by thesame reference numerals and are not described in detail.

As shown in FIG. 15, similarly to Embodiment 5, a distance (S_(C))between electrodes 1006 of electronic component 1004 and a distance(S_(S)) between electrodes 1003 of wiring board 1002 satisfy therelation S_(C)≧S_(S). Angle α between the surface of electroniccomponent 1004 facing solder 1005 and the contour of solder 1005 is notless than 90°. Solder resist 1017 is provided on an upper surface ofwiring board 1002. Solder resist 1017 does not provided at a portion onthe surface of wiring board 1002 facing electronic component 1004. Thisarrangement provides a large space between electronic component 1004 andwiring board 1002. This space permits the clearance between electroniccomponent 1004 and wiring board 1002 to be reliably filled withinsulating resin 1007.

In the case that angle β between the contour of solder 1005 and thesurface of electrode 1003 is an acute angle less than 90°, even whensolder 1005 expands and melts, solder resist 1017 functions as a wallfor preventing solder 1005 from flowing out.

As described above, solder resist 1017 prevents solder 1005 from flowinto the clearance between electronic component 1004 and wiring board1002 even if solder 1005 melts and expands, hence preventingshort-circuiting between electrodes 1003 and 1006.

Exemplary Embodiment 7

FIG. 16 is a sectional view of module 1001B with built-in electroniccomponent 1004 according to Exemplary Embodiment 7 of the presentinvention. The same elements as those of Embodiment 5 are denoted by thesame reference numerals and are not described in detail.

Similarly to Embodiment 5, in module 1001B, a distance (S_(C)) betweenelectrodes 1006 of electronic component 1004 and a distance (S_(S))between electrodes 1003 of wiring board 1002 satisfy the relationS_(C)≧S_(S). Angle α between the surface of electronic component 1004facing wiring board 1002 and the contour of solder 1005 is more than90°.

Solder resist 27 is formed only around electrode 1003. When electroniccomponent 1004 is mounted on wiring board 1002 with solder 1005, solderresist 27 prevents short-circuiting failure at electrodes 1003 and 1006due to flowing out of solder 1005. In addition, since solder resist 27is formed only around electrode 1003, a space between electroniccomponent 1004 and wiring board 1002 can be large. This space allows aclearance between electronic component 1004 and wiring board 1002 to bereliably filled with insulating resin 1007.

Angle β between the surface of electrode 1006 on wiring board 1002facing to electronic component 4 and the contour of solder 1005 is anacute angle less than 90°. Solder resist 27 functions as a wall forpreventing solder 1005 from flowing out even if solder 1005 melts andexpands.

As a result, even if solder 1005 melts and expands, solder resist 27prevents a short-circuiting failure at electrodes 1003 and 1006 due toflowing out of solder 1005 between electronic component 1004 and wiringboard 1002.

A shape of solder 1005 in the modules according to Embodiments 5 to 7may be applied to solder 5 in the modules according to Embodiments 1 to4 with the same advantages.

INDUSTRIAL APPLICABILITY

In a module with a built-in electronic component according to thepresent invention, a clearance between the electronic component and awiring board is reliably filled with an insulating resin. This preventsa melting solder from flowing out of the electrodes when the module ismounted on a motherboard.

1. A module comprising: a first electronic component including first andsecond electrodes; a board including third and fourth electrodes on afirst surface thereof, the third and fourth electrodes being coupled tothe first and second electrodes of the first electronic component,respectively; first and second solders for connecting the first andsecond electrodes of the first electronic component to the third andfourth electrodes of the board, respectively; a first insulating resinfor covering the first electronic component, the first surface of theboard, the first and second solders, and the first to fourth electrodes;a first solder resist provided on the first surface of the board andaround the third electrode; and a second solder resist provided on thefirst surface of the board and around the fourth electrode, the secondsolder resist being separated from the first solder resist at a portionbetween the first electronic component and the board.
 2. The module asdefined in claim 1, wherein the first and second solder resists areprovided only around the third and fourth electrodes, respectively. 3.The module as defined in claim 1, wherein the first insulating resinincludes thermosetting resin, and inorganic filler by a rate rangingfrom 50 wt. % to 95 wt. % having a particle diameter less than aclearance between the board and the first electronic component.
 4. Themodule as defined in claim 1, wherein the first insulating resinincludes a second insulating resin provided among the first electroniccomponent, the board, and the first and second solders, and a thirdinsulating resin made of material different from material of the secondinsulating resin, the first electronic component being located betweenthe third insulating resin and the board.
 5. The module as defined inclaim 4, wherein the second insulating resin includes thermosettingresin, and inorganic filler by a rate ranging from 10 wt. % to 70 wt. %having a particle diameter less than a clearance between the board andthe first electronic component.
 6. The module as defined in claim 4,wherein the second insulating resin has a bending modulus less than 20GPa.
 7. The module as defined in claim 4, further comprising a metalfilm for covering a whole surface of the third insulating resin.
 8. Themodule as defined in claim 1, wherein the first insulating resin has abending modulus less than 20 GPa.
 9. The module as defined in claim 1,further comprising: a second electronic component including fifth andsixth electrodes; seventh and eighth electrodes coupled to the fifth andsixth electrodes of the second electronic component, respectively, andprovided on the first surface of the board; third and fourth solders forconnecting the fifth and sixth electrodes of the second electroniccomponent to the seventh and eighth electrodes of the board,respectively; and a second insulating resin provided between the secondelectronic component and the board, wherein the first resin covers thefirst and second electronic components, the first surface of the board,the first to fourth solders, and the first to eighth electrodes.
 10. Themodule as defined in claim 9, wherein the first resin includes a secondinsulating resin provided between the second component and the board andcovering the third and fourth solders, and a third insulating made ofmaterial different from material of the second insulating resin andcovering the second insulating resin, the first and second electroniccomponents being located between the third insulating resin and theboard.
 11. The module as defined in claim 10, further comprising a wallof solder resist on the first surface of the board at an interfacebetween the second insulating resin and the third insulating resin. 12.The module as defined in claim 10, further comprising third and fourthsolder resists provided on the first surface of the board and around theseventh and eighth electrodes, respectively.
 13. The module as definedin claim 12, wherein the third and fourth solder resists are separatedfrom each other at a portion between the second electronic component andthe board.
 14. The module as defined in claim 12, wherein the third andfourth solder resists are connected at a portion between the secondelectronic component and the board.
 15. The module as defined in claim10, wherein the second insulating resin has a thermal expansioncoefficient larger than a thermal expansion coefficient of the thirdinsulating resin.
 16. The module as defined in claim 9, wherein adistance between the seventh electrode and the eighth electrode is notmore than a distance between the fifth electrode and the sixthelectrode.
 17. The module as defined in claim 1, wherein a distancebetween the third electrode and the fourth electrode is not more than adistance between the first electrode and the second electrode.
 18. Themodule as defined in claim 1, further comprising a metal film forcovering a whole surface of the first insulating resin.
 19. A modulecomprising: an electronic component including first and secondelectrodes; a board including third and fourth electrodes on a firstsurface thereof, the third and fourth electrodes are coupled to thefirst and second electrodes of the electronic component, respectively,wherein a distance between the third electrode and the fourth electrodeis not more than a distance between the first electrode and the secondelectrode; first and second solders for connecting the first and secondelectrodes of the electronic component to the third and the fourthelectrodes, respectively; an insulating resin for covering theelectronic component, the first surface of the board, and the first andsecond solders; a first solder resist provided on the first surface ofthe board and around the third electrode; and a second solder resistprovided on the first surface of the board and around the fourthelectrode, the second colder resist being separated from the firstsolder resist at a portion between the electronic component and theboard.
 20. The module as defined in claim 19, wherein the first and thesecond solders have first and second contours located between theelectronic component and the board, respectively, and the first andsecond contours extend in directions approaching each other as the firstand second contours approach the wiring board from the electroniccomponent.
 21. The module as defined in claim 19, wherein the first andsecond solder resists are provided only around the third and fourthelectrodes, respectively.
 22. The module as defined in claim 19, furthercomprising a fifth electrode electrically connected to the thirdelectrode and provided on a second surface of the board.
 23. The moduleas defined in claim 19, further comprising a metal film for covering awhole surface of the insulating resin.